Rubio talks to reporters in June after a closed door briefing on Capitol Hill.

Hide Caption

7 of 20

Photos:Moments from Marco Rubio's career

Rubio speaks to the media in front of a wall dedicated to the victims of the violence in Venezuela as he shows support for the Venezuelan community at a restaurant in Doral, Florida, in April 2014.

Hide Caption

8 of 20

Photos:Moments from Marco Rubio's career

Rubio speaks to the media at the Doral restaurant in April 2014.

Hide Caption

9 of 20

Photos:Moments from Marco Rubio's career

Rubio checks his phone in March as he arrives for a Capitol Hill news conference to introduce a proposal for an overhaul of the tax code.

Hide Caption

10 of 20

Photos:Moments from Marco Rubio's career

Rubio, left, is greeted as he arrives at a restaurant in Doral in February 2014.

Hide Caption

11 of 20

Photos:Moments from Marco Rubio's career

Rubio, left, and Florida Gov. Rick Scott speak to the media in Doral in February 2014.

Hide Caption

12 of 20

Photos:Moments from Marco Rubio's career

From left, Sens. Cory Booker, Rubio, Kristen Gillibrand and John McCain wait for Obama to deliver the State of the Union address in January 2014.

Hide Caption

13 of 20

Photos:Moments from Marco Rubio's career

Rubio addresses an event held by the American Enterprise Institute for Public Policy Research in January 2014.

Hide Caption

14 of 20

Photos:Moments from Marco Rubio's career

Paralympian Brad Snyder poses with Rubio during a Team USA Congressional visit in November 2013.

Hide Caption

15 of 20

Photos:Moments from Marco Rubio's career

Rubio speaks in November 2013 during a campaign stop for Virginia Attorney General Ken Cuccinelli, the Republican candidate for governor of Virginia.

Hide Caption

16 of 20

Photos:Moments from Marco Rubio's career

Rubio confers with McCain as U.S. Ambassador to Syria Robert Ford testifies before the Senate Foreign Relations Committee in October 2013.

Hide Caption

17 of 20

Photos:Moments from Marco Rubio's career

Rubio, center, speaks to members of the media as Sen. Ron Johnson, left, and Rep. Ron DeSantis listen during a news conference on Capitol Hill in October 2013.

Hide Caption

18 of 20

Photos:Moments from Marco Rubio's career

Rubio returns to the Capitol after meeting with Obama and other Republican leaders about the government shutdown in October 2013.

Hide Caption

19 of 20

Photos:Moments from Marco Rubio's career

Rubio speaks to an aide on Capitol Hill as he arrives for the weekly Senate Republican Policy Committee luncheon in September 2013.

Hide Caption

20 of 20

Myrtle Beach, South Carolina (CNN)It's the riddle of Marco Rubio.

The Florida Republican might be the most natural politician in the 2016 White House field. Yet for all his potential, he's stuck low in the pack of GOP candidates after a riotous summer hijacked by Donald Trump. His aspirational, optimistic brand of conservatism has struggled for traction in a season of seething political anger.

Still, If GOP strategists had sat down to build a candidate to win back the White House, amid the wreckage of 2012, their prototype would look a lot like the youthful Rubio. With silky political skills, an American Dream story rooted in humble beginnings, hawkish national security reflexes and historic potential as a pioneering Latino, Rubio also offers a generational contrast with Democratic front-runner Hillary Clinton.

"Marco Rubio is like Roy Hobbs in baseball: The Natural," said Bob Vander Plaats, a top social conservative activist in Iowa, referring to the movie about a young hotshot prospect played by Robert Redford. "He is very skilled at being a politician."

Even Rubio's foes acknowledge his flair.

Read More

"When Marco Rubio speaks, young women swoon, old women faint and toilets flush themselves," said Dan Gelber, a former Florida House Democratic minority leader, recalling a warning he gave his troops when his silver-tongued rival was the state's speaker. "This guy is really good. Marco is instinctive. He is also very, very disciplined."

But despite his credentials, which also include a statewide power base in the crucial swing state of Florida, the 44-year-old has yet to establish a strong position in the polls in any early voting contest. He failed to get the jump pundits expected after a strong first debate.

Rubio's struggles

His struggles are a reminder that in presidential politics, timing is as important as talent. In an election season that's giving outsiders the advantage, voters aren't very attracted to polished politicians. In fact, the candidates who are prospering amid a storm of anti-Washington anger are those who are not politicians at all, including Trump, Ben Carson and Carly Fiorina.

And it's possible that, after President Barack Obama, GOP voters are not looking to elevate another freshman senator.

Rubio's campaign, however, is not panicking. The senator is working methodically through early states, raising cash at a healthy clip and laying out detailed policy plans, particularly on national security as he vows to rip up Obama's Iran deal and stiffen the U.S. stance toward Russia and China.

"We don't pay much attention to the polls at this stage," said Rubio's communications director Alex Conant. "It's very early in the process ... there are going to be a lot more debates."

He added: "In the long run, Marco is somebody who can unite the party and inspire the nation."

History is on Rubio's side: Summer front-runners rarely prosper once the weather cools and primary voting starts.

But given the scouting reports on Rubio, and buzz that he represents the future of the conservative movement, his polling does seem tepid. He averages seventh place in Iowa and South Carolina polls, came 10th in an NBC/Marist poll published Sunday in New Hampshire, and averages fifth place in national surveys, 20 points behind Trump.

Of course, it's early -- there are five months before the Iowa caucuses, plenty of time for the GOP race to mature, and thoroughbreds to move to the front. But Rubio's low-key start does beg questions about whether he has a viable path to the GOP nomination.

Many Republican veterans feel he will improve over time. And he could benefit from a lack of early scrutiny as rivals like Scott Walker struggle to adapt to a national stage and his mentor, Jeb Bush, risks damage from a clash with Trump.

"Rubio ... has a combination of a factors that can make his fortunes rise if in fact he has the staying power," said Ken Blackwell, a former Republican secretary of state in Ohio. "That means he has to raise the money, he has to develop the organization and capacity in key states, he has to resonate on his message."

In a normal year, Rubio's methodical strategy -- touring battleground states, building a finance and get-out-the vote network, and laying out policy might be shrewd.

Race on steroids

But the 2016 race is on steroids. No one knows how its going to turn out.

"There is just not a lot of oxygen left in the room. Donald Trump sucks the air out of any room he walks into," said Scott Huffmon, a professor of political science at Winthrop University, South Carolina.

Rubio says he's playing the long game, and draws similarities with his 2010 Senate race, in which his tea party-backed campaign fought an establishment candidate and won.

"When I entered that race, the only people who thought I could win all lived in my home. Four of them were under the age of 10," Rubio told crowds in South Carolina and Nevada during recent campaign swings.

Late last month in Columbia, South Carolina, Rubio demonstrated his breadth before an audience of 900 students, getting into detail on poverty reduction, preserving the American dream and threats to U.S. national security.

Rubio held another audience rapt the next morning at a steakhouse in Myrtle Beach, a tea party stronghold. His half-hour stump speech made a case for a candidacy anchored on a conservative approach to a key 2016 theme: the millions of Americans left marooned by the slow-growing economy.

His stump persona suggests a politician in a hurry and a clipped delivery that contrasts with the halting style of Bush, his mentor. It's an emerging paradox about his campaign: While Rubio seems to be struggling to make noise in the GOP race, many Democrats privately say they fear him.

There's no mystery that Clinton was the target of Rubio's initial campaign mantra: "Yesterday's over."

He jumps on chances to engage Clinton. He has said she's desperate for comparing GOP views on women's issues to those of terrorist groups. Rubio has recently stepped up attacks on Clinton over her email controversy, saying it is "disqualifying" for someone seeking the presidency.

But before he can battle the former secretary of state, Rubio must figure out how to confront the insurgent wave powering Trump, Carson and Fiorina.

'First place in February'

"We are trying to build a campaign here," Rubio told CNN's Jeff Zeleny in Puerto Rico last week. "We want to be in first place in February, not in August or September. We have a campaign that is designed to achieve that goal."

While other candidates have tried to match Trump in outrage, Rubio argues that being angry will not solve anything, countering the billionaire's promise to make America great again by arguing the nation is already pretty special.

But he's got an ear to the ground on the economy. He frequently notes concern that millions of people think "the American dream is out of reach," talks about how to cut the cost of college and how free enterprise -- not government power -- is the way to cope with economic volatility. It doesn't hurt that Rubio's father was a bartender and his mother a housekeeper.

It's an approach meant to address perceptions that Republicans simply don't care about those left behind by an economy that seems to favor the wealthy, a narrative that helped tank 2012 nominee Mitt Romney.

While the campaign will not divulge its early-state strategy, it admits Rubio must perform well in Iowa, New Hampshire, South Carolina and Nevada.

"Anyone who wants to win the Republican nomination has to prove themselves in the early states," said Conant.

Rubio may have an opening in South Carolina, where he won support from former senator and tea party champion Jim DeMint, when he ran for the Senate. The state may also be a fit for his fiscal conservatism and robust foreign policy views. His Hispanic heritage meanwhile may be helpful in Nevada, a state where he has wide contacts along with family ties after living there as a teenager. Senior figures in his campaign brain trust also hail from the state.

In Iowa, Rubio could benefit from his backing of insurgent Republican Joni Ernst in her successful midterm Senate race. But a number of Iowa activists expressed private concerns that Rubio had yet to fully commit to the Hawkeye state.

When conservatives are asked about Rubio, they often say they want to find out more. But he doesn't provoke the gushing response reserved for Texas Sen. Ted Cruz, Carson or Trump.

While Cruz can convincingly argue that he lived up to his promise to sabotage what he calls the Washington "cartel," Rubio still has to explain his ill-fated work on a comprehensive immigration reform package, which is radioactive among the conservative grass-roots.

Some key Republicans also question whether Rubio really knows where his base is.

"I think he is trying to thread an awkward needle," said Vander Plaats. "Rubio might be able to be the establishment candidate. But he would also like to be the tea party, outside candidate."

Ultimately, Rubio needs a moment in the spotlight -- not easy to come by in such a crowded Republican field.

"If Marco gets open water he is going to separate himself from a lot of the crowd, " said Gelber. "But I am not sure when that is going to happen."